1. Field of the Invention
The present invention relates generally to telecommunications systems and methods for determining the location of a mobile terminal within a cellular network, and specifically for allowing mobile subscribers to define a privacy profile for positioning.
2. Background and Objects of the Present Invention
Cellular telecommunications is one of the fastest growing and most demanding telecommunications applications ever. Today it represents a large and continuously increasing percentage of all new telephone subscriptions around the world. A standardization group, European Telecommunications Standards Institute (ETSI), was established in 1982 to formulate the specifications for the Global System for Mobile Communication (GSM) digital mobile cellular radio system.
With reference now to FIG. 1 of the drawings, there is illustrated a GSM Public Land Mobile Network (PLMN), such as cellular network 10, which in turn is composed of a plurality of areas 12, each with a Mobile Switching Center (MSC) 14 and an integrated Visitor Location Register (VLR) 16 therein. The MSC/VLR areas 12, in turn, include a plurality of Location Areas (LA) 18, which are defined as that part of a given MSC/VLR area 12 in which a mobile station (MS) (terminal) 20 may move freely without having to send update location information to the MSC/VLR area 12 that controls the LA 18. Each Location Area 18 is divided into a number of cells 22. Mobile Station (MS) 20 is the physical equipment, e.g., a car phone or other portable phone, used by mobile subscribers to communicate with the cellular network 10, each other, and users outside the subscribed network, both wireline and wireless.
The MSC 14 is in communication with at least one Base Station Controller (BSC) 23, which, in turn, is in contact with at least one Base Transceiver Station (BTS) 24. The BTS is the physical equipment, illustrated for simplicity as a radio tower, that provides radio coverage to the cell 22 for which it is responsible. It should be understood that the BSC 23 may be connected to several BTS""s 24, and may be implemented as a stand-alone node or integrated with the MSC 14. In either event, the BSC 23 and BTS 24 components, as a whole, are generally referred to as a Base Station System (BSS) 25.
With further reference to FIG. 1, the PLMN Service Area or cellular network 10 includes a Home Location Register (HLR) 26, which is a database maintaining all subscriber information, e.g., user profiles, current location information, International Mobile Subscriber Identity (IMSI) numbers, and other administrative information, for subscribers registered within that PLMN 10. The HLR 26 may be co-located with a given MSC 14, integrated with the MSC 14, or alternatively can service multiple MSCs 14, the latter of which is illustrated in FIG. 1.
The VLR 16 is a database containing information about all of the MS""s 20 currently located within the MSC/VLR area 12. If an MS 20 roams into a new MSC/VLR area 12, the VLR 16 connected to that MSC 14 requests data about that MS 20 from the HLR database 26 (simultaneously informing the HLR 26 about the current location of the MS 20). Accordingly, if the user of the MS 20 then wants to make a call, the local VLR 16 will have the requisite identification information without having to reinterrogate the HLR 26. In the aforedescribed manner, the VLR and HLR databases 16 and 26, respectively, contain various subscriber information associated with a given MS 20.
Determining the geographical position of an MS 20 within a cellular network 10 has recently become important for a wide range of applications. For example, positioning services may be used by transport and taxi companies to determine the location of their vehicles. In addition, for emergency calls, e.g., 911 calls, the exact location of the mobile terminal 20 may be extremely important to the outcome of the emergency situation. Furthermore, positioning services can be used to determine the location of a stolen car, for the detection of home zone calls, which are charged at a lower rate, for the detection of hot spots for micro cells, or for the subscriber to determine, for example, the nearest gas station, restaurant, or hospital, e.g., Where am I service.
As can be seen in FIG. 2 of the drawings, upon a network positioning request, the Base Station System (BSS) (220 and 240) serving the MS 200 to be positioned generates positioning data, which is delivered to the MSC 260. This positioning data is then forwarded to a Mobile Location Center (MLC) 270 for calculation of the geographical location of the MS 200. The location of the MS 200 can then be sent to a Location Application (LA) 280 that requested the positioning. Alternatively, the requesting LA 280 could be located within the MS 200 itself, within the MSC/VLR 260 or could be an external node, such as an Intelligent Network (IN) node.
In order to accurately determine the location of the MS 200, positioning data from three or more separate BTS""s (210, 220, and 230) is required. This positioning data for GSM systems can include, for example, a Timing Advance (TA) value, which corresponds to the amount of time in advance that the MS 200 must send a message in order for the BTS 220 to receive it in the time slot allocated to that MS 200. When a message is sent from the MS 200 to the BTS 220, there is a propagation delay, which depends upon the distance between the MS 200 and the BTS 220. TA values are expressed in bit periods, and can range from 0 to 63, with each bit period corresponding to approximately 550 meters between the MS 200 and the BTS 220.
Once a TA value is determined for one BTS 220, the distance between the MS 200 and that particular BTS 220 is known, but the actual location is not. If, for example, the TA value equals one, the MS 200 could be anywhere along a radius of 550 meters. Two TA values from two BTSs, for example, BTSs 210 and 220, provide two possible points that the MS 200 could be located (where the two radiuses intersect). However, with three TA values from three BTSs, e.g., BTSs 210, 220, and 230, the location of the MS 200 can be determined with a certain degree of accuracy. Using a triangulation algorithm, with knowledge of the three TA values and site location data associated with each BTS (210, 220, and 230), the position of the MS 200 can be determined (with certain accuracy) by the MLC 270.
It should be understood, however, that any estimate of time, distance, or angle for any cellular system 205 can be used, instead of the TA value discussed herein. For example, the MS 200 can have a Global Positioning System (GPS) receiver built into it, which is used to determine the location of the MS 200. In addition, the MS 200 can collect positioning data based on the Observed Time Difference (OTD) between the time a BTS 220 sends out a signal and the time the MS 200 receives the signal. This time difference information can be sent to the MLC 270 for calculation of the location of the MS 200. Alternatively, the MS 200, with knowledge of the location of the BTS 220, can determine its location.
Existing technology can provide subscribers with the ability to prevent LAs 280 from positioning them in order to protect their privacy. However, in some cases, it is necessary for the specific LA 280 to position the MS 200 regardless of the privacy settings of the particular subscriber. For example, when the LA 280 is an emergency center or a law enforcement agency, the community interest in positioning the MS 200 outweighs the subscriber""s need for privacy. In this case, the privacy settings of the subscriber will need to be overridden in order for the emergency center or law enforcement agency to position the MS 200. In addition, LAs 280 may need to have the ability to override other location settings established by the subscriber. Thus, a Privacy Override Key (POK) (not shown) can be provided by network operators to allow an LA 280 to override the subscriber""s privacy settings in order to obtain the location of the subscriber with a high degree of accuracy.
The POK is typically assigned on an individual LA 280 basis by a Gateway Mobile Location Center (GMLC) (not shown) during the registration of the LA 280 at the GMLC of the PLMN 205 that the LA 280 is located in. Normally, commercial-type LA""s 280 are not allowed to override the subscriber""s privacy settings, e.g., the assigned value of the POK is xe2x80x9cnot overridexe2x80x9d. However, certain specific LA""s 280, such as law enforcement or E-911, which must be capable of positioning a subscriber regardless of the subscriber""s settings, can be assigned a POK with the value xe2x80x9callowed to override subscriber""s privacy settings.xe2x80x9d It should be noted that when the subscriber is roaming, law enforcement LA""s 280 will need, in addition to the POK with the value xe2x80x9callowed to override subscriber""s privacy settings,xe2x80x9d a court order in order to be able to override the MS 200 privacy settings.
Even though a mobile subscriber has established privacy settings, the mobile subscriber may want to allow certain other subscribers or LAs 280 to have the ability to position the mobile subscriber regardless of the mobile subscriber""s privacy settings. Such other subscribers could be, for example, the mobile subscriber""s family or member(s) of a particular group, such as, e.g., in the case where the subscriber is an employee of a taxi company, the operations center or the mobile subscriber""s manager. For those cases, the mobile subscriber may also want to put limits on the ability of those other subscribers or LA""s 280 to position him. For example, the mobile subscriber may only want those LA""s 280 to be able to position the mobile subscriber during certain hours or minutes of the day, certain days of the week or certain days, weeks or months of the year. In addition, the mobile subscriber may want to limit the number of allowable repetitive positionings by a particular subscriber or LA 280 per hour, day, week, or year.
It is, therefore, an object of the present invention to allow a mobile subscriber to define a location privacy profile, which contains a list of subscribers able to position the subscriber regardless of the mobile subscriber""s privacy settings.
It is a further object of the present invention to permit a mobile subscriber to place limits on the ability of the subscribers within the location privacy profile to position the mobile subscriber.
It is still a further object of the present invention to download the mobile subscribers location privacy profile to the an MSC/VLR when the mobile subscriber is roaming within the area served by that MSC/VLR.
The present invention is directed to telecommunications systems and methods for allowing each mobile subscriber that has subscribed to location services to define a Subscriber Location Privacy Profile (SLPP), which contains a list of preferred subscribers or LA""s that have permission to position the mobile subscriber. The SLPP can also define the conditions under which each of the preferred subscribers can position the mobile subscriber. For example, the mobile subscriber can limit the positioning by a particular preferred subscriber or LA to only certain hours of the day, certain days of the week and/or certain weeks of the year, and can limit the number of times that particular preferred subscriber or LA can request positioning of the mobile subscriber during those allowed times. The SLPP can preferably be connected to the mobile subscriber""s main subscription record in the HLR and can be downloaded to the MSC/VLR together the rest of the subscription information when the MS is roaming within the area served by that MSC/VLR. In addition, in preferred embodiments, the mobile subscriber can define, activate, deactivate and delete the SLPP from the MS with a new family of MAP operations, which is similar in handling to Call Independent Supplementary Services (CISS) used within GSM systems.